1. Field of the Invention
The present invention relates to a Light Emitting Diode (LED) driving apparatus, and more particularly, to an LED driving apparatus that can overcome the problem of heat generation by power loss.
2. Description of the Related Art
Light Emitting Diodes (LEDs) are replacing conventional illuminating light sources in more and more illuminating apparatuses because they have the advantages of small size, low power consumption, quick light-emitting operation, and long light-emitting lifetime.
In general, an LED driving apparatus drives an LED by converting an Alternating Current (AC) input into a Direct Current (DC) signal by a converter including a transformer and a smoothing capacitor.
Herein, the transformer has the advantage of electrical isolation between a primary side and a secondary side, but has the disadvantages of large size and high cost.
Also, the smoothing capacitor, which generally uses a large-capacity electrolytic condenser, has the disadvantages of large size and high cost. In addition, the smoothing capacitor has a shorter lifetime than the LED, thus reducing the entire system lifetime.
In order to overcome the above problems, there has been proposed an LED driving apparatus that uses a constant current source instead of a converter including a transformer and a smoothing capacitor.
However, in the LED driving apparatus using a constant current source, a voltage equal to an input voltage minus a voltage of driven diodes is applied to a drain of the constant current source, thus increasing an output resistance of the constant current source.
An increase in the output resistance increases the heat generation and power loss in the LED driving apparatus, thus degrading the reliability of the LED driving apparatus.